I have my iMac connected to my TV using a Menotek display port converter and HDMI cable. It carries both video and sound satisfactorily. Display settings are System Preferences>Displays>Arrangement>check Mirror Displays. For sound they are System Preferences>Sound>Output>Sony TV. My question is how to turn down the screen on the iMac completely when watching movies. As both units are in the same room, the iMac screen is a little disconcerting. I find that I can turn iMac brightness down (independent from the TV) but not completely. I was told by an Apple rep at BestBuy that a Macbook dims all the way but the iMac does not seem to. I hope someone has a workaround.